I was expecting to get a bit more cardio from a BodyPump but experience was different. I felt like I have done a full body strength session. Should I go for less weights? And do I need a rest day between the two. Lastly if I am already doing weights, would it be more effective to replace Body pump with a BodyAttack?
For future viewers-
BodyPump: 60 minute program aimed at high repetitions on common weighted exercises
BodyAttack: 45-55 minute class focused on cardio exercises and done without weights
Your feeling after the BodyPump session is congruent with the types of exercises; you'd have to drop the weight a significant amount to see the workout shift towards cardio. If you're already doing weights, and enjoy your program, dropping BodyPump for BodyAttack will give you the cardio you're seeking. If you like the BodyPump program more than your lifting program, you could consider dropping your own program and then switching off between BodyPump and BodyAttack.
I'm not sure which "two" you're talking about regarding the rest day. In regards to your own program and BodyPump, it would be best to take a rest day in between, as BodyPump hits most major muscles and almost certainly would have overlap with your weight-training plan. If you switch to BodyAttack, you could lift and then do the program the next day, as BodyAttack does not involve weights, and therefore you won't have much overlap.
Bodypump with low/moderate weight selection doesn't make anything what weight lifting can do for your muscles. Bodypump by default is HIIT oriented activity which builds heart muscle stronger and help you improve endurance (low weight selection + many repetitions).
If you want to be focused on building muscles try proper weights within Bodypump session + supersets beforehand. It works really well for me. I do 6 trainings per week (2 classes a day) which include combination of Bodypump/Bodyattack, Bodycombat/Bodypump, Bodypump/Spinning.
I notice a difference for small muscle groups like biceps to perform combination of supersets with heavy weight create fatigue followed by Bodypump less weight/many repetitions cycle.